Conventionally, in a stator coil of a rotating electrical machine, a low-resistance layer is provided on the surface of a coil to prevent discharge in a slot made between a core and a coil.
For example, there is a technique in which a potential grading layer is provided at the end of a low-resistance layer to prevent discharge on the surface of the low-resistance layer during operation of a rotating electrical machine.
Moreover, there is a technique in which a potential grading layer is obliquely provided to prevent discharge between adjacent coils at a coil end.
However, in the conventional technique, though discharge can be prevented in a coil slot, at a core end, and between adjacent coils, discharge for peripheral grounding structures such as an electromagnet shielding plate cannot be prevented. To reduce the length of shaft of a stator, it is effective to greatly bend the end of a coil. In this structure, the distance from the stator coil to a peripheral grounding structure is reduced, and discharge may occur between the stator coil and peripheral grounding structure. Hereinafter, an electromagnetic shielding plate is taken as an example of peripheral grounding structures.
Since an electromagnetic shielding plate is grounded, a stator coil is designed not to cause discharge. Specifically, a stator coil is designed by determining the distance between a stator coil and an electromagnetic shielding plate by the surface potential of a stator coil close to an electromagnetic shielding plate. Therefore, bending of a coil end is limited, and it is difficult to reduce the length of a stator shaft.
In the above circumstances, it is desired to provide a rotating electrical machine, which realizes compactness without decreasing operating voltage, and a coil used for the rotating electrical machine.